As the fall and winter movie seasons take shape, and everyone seems to think they know what the biggest movies of the next few months will be (War Horse, Tintin, Sherlock Holmes 2 etc.), there's still one gigantic question mark. Yes, David Fincher's adaptation of The Girl With The Dragon Tattoo is based on a wildly best-selling book, is a follow-up to the very popular The Social Network, and features a murderer's row of experienced actors to back up the girl already picked as this year's big breakout, Rooney Mara. But it's also a dark, very violent story that requires a bunch of actors to put on fake Swedish accents and talk about very intricate details of Swedish journalism and the legal system-- and that's before you get into the massive family tree at the center of the mystery.

Yes, it's going to be a challenge, which is why Sony has had a slow, steady and uniformly excellent marketing campaign going for months now. The latest entry is this Vogue cover story, in which Mara poses like a slightly terrifying glamourpuss and Fincher reveals a few details about the process of casting her… including why he didn't cast Scarlett Johansson after her great audition. Here's how he tells it:

“We flew in people from New Zealand and Swaziland and all over the place. Look, we saw some amazing people. Scarlett Johansson was great. It was a great audition, I’m telling you. But the thing with Scarlett is, you can’t wait for her to take her clothes off.” He stops for a moment. “I keep trying to explain this. Salander should be like E.T. If you put E.T. dolls out before anyone had seen the movie, they would say, ‘What is this little squishy thing?’ Well, you know what? When he hides under the table and he grabs the Reese’s Pieces, you love him! It has to be like that.”

For her part, Mara opened up about how grueling the audition process was for her, apparently nothing compared to the 2,400 takes Fincher had her do in her four days of shooting on The Social Network. At one point, when he called her in asking for photos of her on a motorcycle to see if she was right for the part, she was ready to throw in the towel and give up:

“I was ready to throw down. I was thinking, You either think I can be this girl or you don’t, but I need to move on with my life. He sat me down and gave me this long spiel about all the bad things that are going to come to whoever plays this part. He said something like, ‘Vivien Leigh was incredible in A Streetcar Named Desire, but she will always be Scarlett O’Hara, and you need to be prepared for that.’ ”

There are tons more details like that in the article, including Mara admitting how much she hated working on the Nightmare on Elm Street remake and the man who acts opposite her in a key rape scene, Yorick van Wageningen, saying he "spent a day crying in my hotel room" before shooting the scene. Read the whole thing here, and I promise you won't be thinking about whether or not Scarlett Johansson would have been good in it. Months before the movie comes out, Rooney Mara is already feeling like the crucial heart of Dragon Tattoo. As Fincher told the Vogue reporter, "Oh, man. She’s a weirdo. She’s a great weirdo.”